Question: Express this number in scientific notation. $0.004\;421$
Explanation: Count the zeroes to the right of the decimal point before the leading $\leadingColor{4}$ : there are $2$ zeroes If you count the leading digit $\leadingColor{4}$ and those zeroes , there are $\exponentColor{3}$ digits to the right of the decimal point. So: $0.004\;421 = \leadingColor{4}.421 \times 10^{\exponentColor{-3}}$